Spherical coil for variometers



May 18, 1948. E. E. COMBS SPHERICAL COIL FOR VARIOMETEI KS Filed Sept.6, 1944 2 Sheets-Sheet 1 INVENTOR DWARD acomss .BY flaw/v. M, 9 M.

ATTORNEY May 18, 1948. E. E. coMBs SPHERICAL COIL FOR VARIOMETERS FiledSept. 6, 1944 2 SheetsSheet 2 moo 1 Non INVENTOR. EDWARD E. COMBSATTORNEY Patented May 18, 1948 UNITED STATES PATENT OFFICE 2,441,564SPHERICAL COIL FOR VARIOMETERS Edward E. Combs, Long Branch, N. J.

Application September 6, 1944, Serial No. 552,859

(Granted under the act of March 3, 1883, as

7 Claims.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes, without the payment to me ofany royalty thereon.

This invention relates to spherical coils used in radio tuning circuits.The invention discloses the structure of the spherical coils and themethod of making them.

It is very well known in the radio art that the spherical coils whenused in connection with variometers are much more effective than thecylindrical coils because the spherical coil rotor may be coupled muchcloser to the cylindrical stator of the variometer thus enabling one tospan much wider frequency band with the variometers of this type, thecombination being capable of replacing as many as six fixed R. F. coils.Although the advantages of the spherical coils are well known in theart, their use has been somewhat limited because no simple manufacturingmethods were available, and, as a consequence, the majority ofvariometers used cylindrical rotors.

The invention discloses a simple method of making the spherical coilsand a structure for supporting them after they are wound.

It is, therefore, an object of this invention to provide a simple jigfor making spherical coils as well as to improve the structural andelectrical features of the coils of this type.

The novel features which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My invention,itself, however, both as to its organization and method of operation,together with the objects and advantages thereof, may best be understoodin connection with the following description and accompanying drawingsin which,

Fig, 1 is a side view of a jig used for making spherical coils,

Fig. 2 is an end view of Fig. 1,

Fig. 3 is a side view of a finished spherical coil,

Fig. 4 is a cross sectional view of an additional coil jig which may bealso used for making spherical coils,

Fig. 5 is the side view of a finished spherical coil made in accordancewith the method illustrated in Fig. 4,

Fig. 6 is a side view of a modified form of a jig,

Fig. 7 is a side view of a wire holder which is used for transferringthe wound wire from the jig illustrated in Fig. 6 onto the coil frameillustrated in Fig. 8,

Fig. 8 is an isometric view of a frame equipped with ceramic pieces forsupporting wire, the

amended April 30, 1928; 370 O. G. 757) ceramic pieces being mounted on aring made of plastics material,

Fig. 9 is a side view of the coil illustrated in Fig. 8 with the wirewound upon it.

Referring now to Fig. l the jig for making the coil. includes a shaftI9, which is ordinarily mounted in a lathe, enlarged at its outer end soas to form a ring I2, the ring being provided with a plurality ofthreaded pins M which are permanently mounted on the ring along acircle, as illustrated more clearly in Fig, 2. The center of this circlecoincides with the longitudinal center-line of shaft I0. Ring I2 is alsoprovided with a centrally mounted pin IS, the center line of pin iscoinciding with the longitudinal center line of shaft in. Pin I6 isthreaded at both ends, and the right end of the pin is used for fixedlymounting pin IS on ring l2 while the left end is used for holding anouter ring is against the truncated-sphere form-pieces 20 and 22 bymeans of a wing nut 24. The form-pieces 20 and 22 represent a pluralityof pieces which,

when mounted on the pins 14, the inner and outer corners 25 and 26 ofthese pieces rest on shoulders 28 and 30 provided for this purpose onthe rings I2 and I8, thus forming a truncated sphere, as illustrated inFig. 1. The form pieces are provided with a slot used for mounting aring 32 made of any suitable insulating material such as Bakelite orpolystyrene or any other non-conductive substance which does not introduce high radio frequency losses in the coil. The form pieces 20 and 22are also provided with the longitudinal slots 34 (see Fig. 2), theseslots being used for mounting the coil supporting ribs 36 made of thesame material as ring 32. The ribs 36 are held in their slots 34 byrings l2 and [8 which are provided for this purpose with recesses 38 and40, the ribs 36 protruding into these recesses.

The outer surfaces of the form pieces are provided with grooves 42 whichare used for guiding the wire of the coil from one end of the form tothe other during the winding operation. The grooves thus form an outerthread of the form, the number of turns in the coil being determined bythe pitch of this outer thread.

The jig illustrated in the Figs. 1 and 2 is assembled and prepared forwinding the coil upon it in the following manner: shaft I0 is mounted ina lathe and the form pieces 22 are slipped onto pins l4, corners 25engaging shoulder 28 provided in ring l2. This aligns the form pieces 22so that they form the right side of the form. Ring 32 is then placed inthe recesses provided in the pieces 22 and the form pieces 20 are thenslipped into their proper position, ring 32 aligning the form pieces 20with the pieces 22. When this is accomplished the preformed coil ribs 38are placed into slots 34 (Fig. 2) and recesses 38, and the entireassembly is then rigidly clamped together by sliding ring [8 intoengagement with the form pieces 20v and ribs 36, and by tightening thewing nut 24. The jig is now ready for use. The winding operation isperformed by clamping the free end of the wire by means of aclamp 44provided for this purpose on ring |8,'and, upon fastening one end of thewire in this manner to, the jig, the jig is rotated by the lathe. Thewire is passed through a heater before it comes into. contact with theform and is guided into the grooves 42 by hand or any suitablemechanical guide. be suitable consists of a frame held by the compoundrest of the carriage of the lathe, and a wire-guiding orifice supportedby the frame. The orifice can be adjusted to introduce the desireddegree of friction between the orifice and the wire, which in turnproduces the desired degree of tension onto the wire during the windingoperation. The wire is heated, preferably by electrical means; prior toitspassage through the orifice, and is guided to follow the grooves 4.2by sliding the carriage. Since the temperature of the wire has beenraised by the heater, it imbeds itself in the polystyrene ribs 36 uponcoming into contact with them. Winding operationis continued until theentire .form has been covered with the wire whereupon the lathe isstopped and the wire is cut off from the wire spool. The wire is nowheld in place by the solidified polystyrene. In order to dismantle thejig wing nut 24 is unscrewed, ring 18 isremoved from the pins and theentire coil form slid oil pins [4 whereupon the form pieces 20 and 22collapse and are removed from the coil, one form piece'at a time. Ring32 may be cemented to the ribs 36 either before winding of the wire orafter the form pieces have been removed, the ring upon being cemented tothe ribs, representing a centrally located rib-reinforcing ringimparting rigidity to the entire coil and holding ribs 36 in. fixedrelationship with respectto the coil. The only remaining operation tofinish the coil resides in fastening coil shafts 300, 302 Fig. 3 withtheir bifurcated ends 3.08, 3H] to the ringwhich is accomplished bymeans of bolts 304 and 306, the two ends of the wire are then connectedto the shafts by means of lugs 3l2, 3I4, the shafts being madeofconductive material.

Exceptionally rigid spherical coils are produced by the methodillustrated in the Figs. 1 and 2, the coils having an additionaladvantage that only very limited amount of wire-supporting in! sulationis used for obtaining the desired. result. Accordingly the coils of thistype have small R. F. losses and high Q values.

Fig. 4 illustrates anothercoil form which may be used to acocmplishthesame result. In Fig. 1 two series of form pieces 20 and 2 2 are used forobtaining the spherical form, the form pieces being separated from eachother in the middle. Split type structure is used since it is necessaryto insert ring 32 between the form pieces which separates the form intotwo symmetrical halves. In; Fig. 4 ring 32 has been completelyeliminated, and as a consequence the form is made of a plurality ofpieces 400 which are identical in all respects to the pieces 20 and 22in Fig. 1 except that the recesses for ring 32have been eliminated Onetype of mechanical guide foundv to and the sides joined together to formone piece 400. These pieces are slipped over pins I4 in the same manneras pieces 20 and 22 in Fig. 1, and the functioning of the entireassembly from then on is identical in all respects to the functioning ofthe assembly illustrated in Fig. 1. As in Fig. 1 ribs 402 are used foractually supporting the wire, these ribs being held in fixed positionwhen the coil is wound in a manner similar to that illustrated inFig. 1. Two of these ribs are provided with bushings 404 and 406 havinga centrally located-hole'408. These bushings are used for mounting coilshafts 500 and 502 as illustrated in Fig. 5.

The coil produced with the form illustrated in Fig. 4jis illustrated inFig. 5. It does not differ markedly from the coil illustrated in Fig. 3except-that the. centrally located ring 32 has been completelyeliminated and the coil shafts in stead of being mounted on ring 32 arenow mounted on ribs. 405 in a manner clearly illustrated in Fig. 5. Theadvantage of the vcoil illustrated in Fig. 5, ascompared to the coilillustrated in Fig, 3, resides in the fact that a narrower spacing maybe used between the central turns of the coil since shafts 500-and 502are now equipped with threaded pins 504 and 506 which do not require asmuch clearance between the turns as the bifurcated joints 308 and 3l0 inFig. 3.

Figs. 3 and 5 disclose that type of spherical coil which uses plastics,such as polystyrene, for supporting the wire. Uses of the variometer areencountered when the variometer is subjected to such heavy loads thatthe coils reach sufliciently high temperatures either to melt orcarbonize the supports made of plastics. When such heavy usage iscontemplated, it is obvious that the coils illustrated in Figs. 3' and 5are unsuitable, and ceramic material must be used for supporting thewire of the coil.

Fig. 8 illustrates such coil where the wire supporting bridges 800 aremade of ceramic material, the bridges being mounted on a ring 802 madeof plastics. The outer surfaces 803 of the bridges are grooved forholding the wire, and are provided with extensions 804 and 808 which fitintothe recesses provided for this purpose in ring 802. In order tostiffen the structure the ceramic bridges and the ring are provided withsuitable holes 808 which are used formounting plastic pins which act asadditional elastic means for holding the ceramic bridges in elasticengagement with the ring. A two-piece shaft 810 and 812 ofthe coil ismounted in this instance on ring 802 by means of threaded ends 814 andnuts BIB (only one end is visible in the figure). The woundv wire isconnected to the shaft by means of lugs 8 18. The advantage of thestructure illustrated in Fig. 8 resides in the fact that ring 802 ismade of plastics thus providing a resilient base for the ceramic pieces,the resiliency of the ring and the resiliency of the connectionsbetween. the ring and the bridges contributing markedly to the abilityof the coil to absorb occasional severe shocks which are apt to takeplace when the equipment is subjected to unusually severe usage. In theprior art the entire coil supporting frame is made of ceramic materialwhich results in a-verybrittle frame not capable ofabsorbing anymechanical shocks. This is not the case in Fig. 8 since the resilienciesof the ring and of the joints are so proportioned that they are capableoi. absorbing very severe shocks. when the variometer is in service, andis accidently dropped, the shock is transmitted to the coil throughshafts 819, BIZ, and since the shafts are mounted in the resilient ring892, the shock is absorbed, in the main, by the ring and the bridge-ringpins, and is transmitted to the c..- ramic bridges only in a subduedform. When the ring is made of the ceramic material it ordinarily cracksresulting in the collapse of the entire coil,

In order to wind the coil frame illustrated in Fig. 8, a coil form 690illustrated in Fig. 6 is used. It consists of a spherical metal form 699slidingly mounted on a mandrel 692, the mandrel being mounted in a lathewhich revolves the form when a wire 694 is wound upon it. A clamp 606 isprovided which is used for clamping the free end of the wire, and afterthe wire has been clamped, the form is rotated and the wire is wound onthe form, the wire following grooves 699 provided for this purpose onthe form. After the form has been completely wound the rotation of theform is stopped, and the opposite end of the wire is clamped by means ofa clamp BIB similar to clamp 696. The wire is then cut off and the nextstep consists of transferring the wire wound on form 699 onto the frameillustrated in Fig. 8.

This transfer is accomplished by means of a wire holder illustrated inFig. 7, which consists of four projections 100, I02, 194 and 196 joinedtogether at I98, the inner surfaces of the projections being providedwith grooves H9, H2 for holding the wire. Only one wire holder isillustrated in Fig. 7, but to accomplish the transfer of the wire fromthe form 609 onto the frame illustrated in Fig. 8, two wire holders areused simultaneously, the second holder being identical to the oneillustrated in Fig. 7. After removing form 680 from the mandrel, the twoholders are slipped over form 699, which they fit snugly, clamps 60B,619 are removed, and the wire is out in the middle of the coil. Becauseof the springing action of the wire, it unwinds itself slightly, andthis unwinding of the wire transfers it to the holders. The holders arethen removed from form 609, and are placed on the frame illustrated inFig. 8. The outer free ends 910 and 9l2 of the wire are then clamped tothe ceramic bridges 899 by means of clamps 909, 992, as illustrated inFig. 9, and after the outer ends have been thus secured to the ceramicbridges, the inner ends 996, 908 of the wire are pulled tightly againstthe bridges, thus transferring the Wire from the holders onto the coilframe, and joined together by soldering as illustrated at 904. The outerends 910 and 9l2 are then connected to the lugs 8l8 (only one lug isillustrated in Fig. 8). The clamps 990 and 992 are then removed and thecoil is ready for its mounting in the variometer. In the majority of thecases the variometer structure may be such that connecting of the outerends 910 and 912 to the lugs must be performed within the variometerafter the spherical coil has been inserted into the stator. In eithercase the final connections are the same.

I claim:

l. A jig for winding a spherical wire coil for a variometer said jigincluding a shaft, a plurality of pins in fixed relationship withrespect to said shaft, a plurality of truncated-sphere form-pieces insliding engagement with said pins, said pieces, when mounted on saidpins, forming a spherical form for winding said coil, and a clampingring for rigidly holding said pieces during the winding operation ofsaid coil.

2. A jig for winding a spherical coil as defined in claim 1 in whichsaid form-pieces are so constructed and arranged as to form acollapsible structure removable from said coil upon completion of thewinding operation of said coil and upon sliding of said form off saidpins.

3. A jig for winding a spherical coil as defined in claim 1 in whichsaid form pieces further include recesses for holding wire-supportingribs for said coil.

i. A jig for winding a spherical coil as defined in claim 1 in whichsaid form pieces further include recesses for holding wire-supportingribs and a centrally mounted ring for centrally bracing said ribs uponremoval of said form pieces.

5. A combination including a coil frame for winding a sphericalwire-coil on said frame, said frame including a plurality ofwire-supporting ribs, a plurality of form-pieces supporting said ribs,said ribs fitting into said form-pieces whereby the outer surfaces ofsaid form-pieces and said ribs form a spherical wire-supporting surfaceduring the winding operation of said coil, a shaft, a plurality of pinsin fixed relationship with respect to said shaft, said form-pieces beingslidingly mounted on said pins, and a clamping ring for rigidly holdingsaid form-pieces and said ribs against said shaft during the windingoperation of said coil.

.6. A combination as defined in claim 5 in which said ribs and saidform-pieces are dimensioned so as to allow the removal of saidform-pieces out of said spherical wire-coil upon the completion of thewinding operation, removal of said clamping ring, and sliding of saidform-pieces oif said pins, said form-pieces thus acting as a collapsiblewire-winding jig for said coil.

7. A combination as defined in claim 5 in which said ribs are made ofthermoplastic material, said wire being partially embedded in andrigidly retained by said ribs.

EDWARD E. COMBS REFERENCES CITED The following references are of recordin the file of this patent:

UNITED STATES PATENTS Number Name Date 1,640,821 Cocks Aug. 30, 19271,853,148 Rigante Apr. 12, 1932 1,888,541 Rigante Nov. 22, 19321,965,330 Apple July 3, 1934 2,013,764 Putnam Sept. 30, 1935

